Interfacing startKIT to 5V
Posted: Sat Jan 14, 2017 6:44 am
Hi Guys,
1st post!
I've been playing around with the startKIT for sometime now and have finally decided to start interfacing it to some TTL level circuitry but am not having any luck with any output.
I'm feeding a 74AHCT125 5V on Vcc(pin 14) via a 5V(7805) power regulator from 12V. Triple checked the pinout and it all appears good. Vcc @ 4.99V. and grounded on pin 7.
- I've got pin 1(OE) on the 125 IC tied to ground.
- XS1_PORT1F is then connected directly to pin 2 on the 125 IC.
- probing pin 3 with a DSO
Checked the StartKITS's 1F port with a DSO and my 100Hz square wave is outputting correctly @ 3.36V, the 125 only has a tiny ~200mV voltage on pin 3 which echos the input on pin2. Shouldn't this be 5V? Tried a 2nd chip, same result.
Am I missing something really basic here?
Thanks in advance.
Ian
1st post!
I've been playing around with the startKIT for sometime now and have finally decided to start interfacing it to some TTL level circuitry but am not having any luck with any output.
I'm feeding a 74AHCT125 5V on Vcc(pin 14) via a 5V(7805) power regulator from 12V. Triple checked the pinout and it all appears good. Vcc @ 4.99V. and grounded on pin 7.
- I've got pin 1(OE) on the 125 IC tied to ground.
- XS1_PORT1F is then connected directly to pin 2 on the 125 IC.
- probing pin 3 with a DSO
Checked the StartKITS's 1F port with a DSO and my 100Hz square wave is outputting correctly @ 3.36V, the 125 only has a tiny ~200mV voltage on pin 3 which echos the input on pin2. Shouldn't this be 5V? Tried a 2nd chip, same result.
Am I missing something really basic here?
Thanks in advance.
Ian